I'm trying to install aftermarket amplifiers in my Terrain. I have never been so aggravated trying to install a system. It seems they have created harnesses and plugs for every other GMC or Chevy model except this one. I have been researching for months with no luck. My truck has the 7" screen which controls the rear speakers, and the factory amplifier controls the front speakers. So running my 4channel amplifier to my factory harness to power the door speakers looks impossible. I have bought a full setup for this truck and can't install it without splicing and splitting wires or losing retention on certain functions. It'* a nightmare I like the truck but hate the fact that it'* so difficult to beautify the sound system to my liking. The only thing that I have done is upgrade my door speakers with Orion XTR'*

Does your truck have the Pioneer system or not?

Either way you can get speaker wiring harnesses,

Metra 72-5601 Speaker Wiring Harness

https://www.crutchfield.com/p_120725...*.html?tp=3097

I have never tried, but I don't see why you could not run new speaker wires to your existing speakers, and use the harness to connect to them.
Not sure how going from the current deck to a aftermarket amp will work, but it has to be possible, hopefully somebody is better able to help you.

Till then if you know whether or not your head unit is Pioneer then go here and maybe this can help.
https://www.crutchfield.com/car/outf...car.aspx?g=100

Moved to the Audio & aftermarket electronics section for better visibility.

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